Adding Chinese translation prepared by Liping Chen, MSU
Merge pull request #22 from openwebwork/release/2.7

Release/2.7
Make OPL the default library instead of NPL

This addresses issue #85
Add explanations for 'avoid_recording_answers' and 'don't_log_answers'.

The first gives permission to the user to NOT have their grades recorded.
The second means that those users and higher do not have their answers logged in the logfiles or in the pastAnswer database.  This can be used to keep TA and instructor answers from corrupting the data collected in those files.
Use internal WWsafe.pm instead of system Safe.pm
Add JSON  requirement for use with Sage calls
Fix default address for libraries.

correct library to libraries
Obtain version number from file VERSION (variable name: $WW_VERSION)
Merge branch 'develop' into hotfix0

Conflicts:
	conf/localOverrides.conf.dist
Merge branch 'develop' of github.com:openwebwork/webwork2 into develop